1. Field of the Invention
This invention concerns a novel method for placing a medical agent into a vessel of a patient, in particular, placing embolic coils into an aneurysm of the brain.
2. Description of the Prior Art
For many years physicians have been placing various devices within a blood vessel of the human body in order to treat aneurysms or to occlude a vessel at a particular location. Such devices are placed within the aneurysm or vessel using a deployment system. When a device is deployed into the vessel but misses its intended position, it is difficult, if not impossible to retrieve or reposition the device. To help alleviate this problem, a delivery system is employed to increase the probability of placing the device precisely at a pre-selected position. A variety of delivery systems exist to provide stability and increase deployment accuracy. The combination of different devices, deployment systems, and delivery systems provide physicians with reliable methods of treating aneurysms.
Various types of devices are placed within an aneurysm or a vessel to occlude the flow of blood through the vessel by promoting thrombus formation at a particular location. Such devices include dilation balloons, radiopaque fluids, liquid medications, and embolic coils. Embolic coils may take the form of helically wound coils, randomly wound coils, coils wound within other coils, or many other coil configurations. These coils are generally formed of radiopaque metallic materials, such as platinum, gold, and tungsten, or alloys of these metals. Often times, several coils are placed at a given location in order to occlude the flow of blood through the vessel.
One example of an embolic coil design is disclosed in U.S. Pat. No. 6,179,857 entitled, “Stretch Resistant Embolic Coil With Variable Stiffness.” The coil is a helically wound coil in which various combinations of adjacent turns are spot welded together to create a stretch resistant coil of a pre-selected flexibility. Another coil configuration is disclosed in U.S. Pat. No. 6,183,491 entitled, “Embolic Coil Deployment System With Improved Embolic Coil,” which shows an embolic coil having a relatively flexible proximal portion which resists stretching.
Also, U.S. Pat. No. 5,853,418 entitled, “Stretch Resistant Vaso-occlusive Coils,” discloses a helically wound coil having a polymeric stretch resisting member extending through the lumen of the coil and fixedly attached to both the distal end and the proximal end of the coil. Other examples of coil configurations are disclosed in U.S. Pat. No. 5,334,210 entitled, “Vascular Occlusion Assembly” and U.S. Pat. No. 5,382,259 entitled, “Vasoocclusion Coil With Attached Tubular Woven Or Braided Fibrous Covering.” With all coil designs, it is important that embolic coils remain very flexible for traveling through vessels when used with deployment systems.
A variety of deployment systems are available for placing embolic coils within an aneurysm or vessel. An example of such a system is disclosed in U.S. Pat. No. 6,113,622 entitled, “Embolic Coil Hydraulic Deployment System,” assigned to the same assignee as the present patent application. The disclosure of the above patent is incorporated into and made part of this patent application. The hydraulic embolic coil deployment system uses fluid pressure which is applied to the distal section of the deployment catheter for expanding the distal section radially to release the embolic coil at a pre-selected position.
Another coil deployment system utilizes a deployment catheter having a socket at the distal end for retaining a ball which is bonded to the proximal end of the coil. The ball is placed in the socket within a lumen at the distal end of the deployment catheter, and the deployment system is then moved into a vessel to place the coil at a desired position. Then, a pusher wire with a piston at the end is pushed distally from the proximal end of the deployment catheter to thereby push the ball out of the socket and release the coil at the desired position. This system is disclosed in U.S. Pat. No. 5,350,397 entitled, “Axially Detachable Embolic Coil Assembly.”
Also, U.S. Pat. No. 5,263,964 entitled, “Coaxial Traction Detachment Apparatus And Method,” discloses another coil deployment system. This system uses glue or solder for attaching the embolic coil to a guidewire which is, in turn, placed within a flexible deployment catheter for positioning the coil within the vessel at a pre-selected position. Once the coil is at the desired position, the coil is restrained by the deployment catheter, and the guidewire is pulled from the proximal end of the deployment catheter causing the coil to be detached from the guidewire and released from the deployment system.
Examples of other deployment systems are disclosed in U.S. Pat. No. 5,122,136 entitled, “Endovascular Electrolytically Detachable Guidewire Tip For The Electroformation Of Thrombus In Arteries, Veins, Aneurysms, Vascular Malformations And Arteriovenous Fistulas” and U.S. Pat. No. 5,108,407 entitled, “Method And Apparatus For Placement Of An Embolic Coil.” Even though fluoroscopic visualization shows physicians general movement of an embolic coil through the vasculature of the body and the use of coil deployment systems allow physicians to control when the embolic coil is released, it is still difficult to precisely place a coil at a pre-selected location, such as a location within an aneurysm. However, with the use of a delivery system, it is possible to stabilize the deployment system within a vessel in order to more precisely place an embolic coil.
An example of such a delivery system is disclosed in U.S. patent application Ser. No. 09/894,735, entitled “Method And Apparatus For Placing A Medical Agent Into A Vessel Of The Body,” filed on Jun. 28, 2001 and in U.S. patent application Ser. No. 09/894,421, entitled, “Method And Apparatus For Placing A Medical Agent Into A Vessel Of The Body,” filed on Jun. 28, 2001, both assigned to the same assignee as the present patent application. These patent applications are incorporated by reference and are made a part of the present patent application. The delivery catheter disclosed in this patent application has two lumens. The first lumen has a shape retaining wire which extends therethrough for shaping an intermediate section of the delivery catheter into a generally U-shaped configuration. The second lumen has a side opening at a location within the intermediate section of the delivery catheter. The side opening is positioned over an aneurysm, and then the embolic coil deployment system is inserted through the second lumen and into a position proximal the aneurysm. The U-shaped delivery catheter stabilizes the deployment system as the embolic coil is released into the aneurysm.
Another delivery system used to stabilize a coil deployment system is disclosed in U.S. patent application Ser. No. 09/878,530 entitled, “Delivery System Using Balloon Catheter,” filed on Jun. 11, 2001 and assigned to the same assignee as the present patent application. The delivery catheter disclosed in this patent application includes a balloon adjacent to the distal end and an inflation port at the proximal end of the catheter for inflating the balloon. The delivery catheter is positioned within the vessel of a patient, and the balloon is inflated to stabilize the position of the delivery catheter. Then, an embolic coil deployment system is introduced into the delivery catheter and through a side opening of the catheter to deliver the embolic coil into the aneurysm.
When physicians use a delivery system in combination with a coil deployment system, the delivery system stabilizes the coil deployment system, and the coil may be placed with greater accuracy. Therefore, it is an objective of this invention to provide a method for placing embolic coils with increased accuracy. Furthermore, it is an objective to provide a system which is relatively simple in construction and easy to use.